When you visit the Snowy Range in the
Medicine Bow National Forest, you notice something—brown trees. Since 2008, this high alpine forest
west of Laramie by way of highway 130 has undergone a considerable
transformation caused by a bark beetle epidemic.
There are many species
of bark beetles in the United States, and uncontrollable bark beetle outbreaks
are occurring in forests throughout the country. In the high alpine forest surrounding
the
Glacier Lakes Ecosystems Experimental Site (GLEES) near the Snowy Range Mountains,
the spruce beetle is the dominate species of bark beetle present and tree mortality
is noticeable in this Wyoming Engelmann spruce-subalpine fir forest.
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These photos show the changes in the forest near GLEES from 2003 to 2013.
Photo Credit: John Frank
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Spruce beetles aid in killing trees by exposing them to blue
stain fungi which colonize the xylem of the attacked trees; thus, not allowing water
to travel through the tree. Although spruce
beetles can be a part of healthy forest cycle, under epidemic conditions spruce
beetles drastically impact forests by attacking large populations of larger
diameter trees.
At GLEES, University of Wyoming scientists, including
members of the
Wyoming Center for Environmental Hydrology and Geophysics
(WyCEHG), have an ongoing partnership with the U.S. Forest Service to monitor
spruce beetle impacts there and assess how this epidemic has changed forest
conditions.
Last Friday, UW doctoral student, John Frank, discussed
findings from his research at GLEES on changes in the ecosystem due to tree mortality.
John is not only working towards earning his Ph.D. within the
Program in Ecology, but he is also an employee of the U.S. Forest Service Rocky Mountain
Research Station. With support from his UW Ph.D. advisor,
Dr. Brent Ewers, John
discovered that to accurately model predictions of ecological conditions
(ecosystem fluxes of carbon dioxide and water vapor) after disturbance from the
spruce beetle epidemic, changes in tree physiology have to be accounted for in
addition to the observed mortality of the trees.
To get to this conclusion, John evaluated six years of data
which was collected during the progression of the spruce beetle epidemic.
With WyCEHG scientists and partners examining impacts on
forests from bark beetle disturbance, researchers and managers will be better
able to understand how forest ecology is changing and how to predict ecological
changes in the future.
By: Elizabeth Nysson
Sources used:
Interview with Dr. Brent Ewers by
Elizabeth Nysson on March 4, 2014.
“How much does a spruce beetle epidemic
alter ecosystem carbon and water processes?” Department of Botany Seminar; John
Frank, Ph.D. Student, Botany Department, PiE; Friday, February 28, 2014.
“Ecosystem CO2/H2O fluxes are explained
by hydraulically limited gas exchange during tree mortality from spruce beetles.”
(IN REVIEW: Journal Geophysical Research-Biogeosciences) John M. Frank, William
J. Massman, Brent E. Ewers, Laurie S. Huckaby, José F. Negrón; U.S. Forest
Service, Rocky Mountain Research Station, 240 W. Prospect Road, Fort Collins,
Colorado, 80526, USA; Department of Botany and Program in Ecology, University
of Wyoming, 1000 E. University Avenue, Laramie, Wyoming, 82071, USA